This invention relates to photographic apparatus and, more particularly, it concerns an apparatus for positive photographic vignetting.
Both negative and positive vignetting are known photographic techniques used to set off a particular image region of a photograph by either darkening, lightening, coloring or blurring the area around the image region. For example, negative vignetting using either an opaque, colored or translucent mask in front of an objective lens of a camera to obstruct or reduce transmission of scene light to a selected portion of an exposure is disclosed in U.S. Pat. No. 4,107,716 issued to Irving Pfefer. Negative vignetting may also be accomplished by placing an opaque or translucent template or transparency at the focal plane and adjacent the film within a camera as disclosed for example in U.S. Pat. No. 4,304,471 issued to Mary R. Jones.
Positive vignetting generally entails transmitting diffused light to a region of the film corresponding to the desired vignetted portion to increase non-imaging illumination of this region as disclosed in U.S. Pat. Nos. 425,812 issued to Hamlin I. Lloyd on Apr. 15, 1890 and 3,528,737 issued to James R. Denner on Sept. 15, 1970. Additionally, it is known to introduce auxiliary light to this region to provide increased illumination to the vignetted portion or to gradually fade the subject image into a light background. As disclosed in U.S. Pat. No. 2,972,931 issued to Walter J. Roob, positive vignetting may be accomplished using a set of auxiliary light bulbs and a vignette in the bellows of an enlarger. As disclosed in U.S. Pat. No. 4,436,400 issued to Phillip S. Charis et al, positive vignetting is produced by the addition of an auxiliary light source and vignette apparatus to a camera lens. Positive vignetting in conjuction with an image carrying template has also been provided to produce a composite image, by utilizing a thick transparent plate affixed on and covering the full face of a camera, and extending between a vignetting aperture over the lens to the camera strobe to light pipe strobe illumination to the plate aperture.
There exists a need for a simple, lightweight positive vignette producing apparatus which does not require the use of an auxiliary light source other than an existing flash unit.